1. Technical Field
The present invention relates to a data reproducing device, a hard disk and a data storing disk having a function to prevent an unlawful copy mainly. The present invention further relates to a data reproducing device, a hard disk and a data storing disk capable of realizing a user-friendly function at a reasonable price.
2. Related Art
In the analog interface of an AV device, there have been taken various measures for preventing unlawful copies. In the digital interface including the IEEE1394 for transmitting video or audio works, too, similar measures have been taken by using the 5C-DTCP (SC Digital Transmission Content Protection system, as will be briefly referred to as the “DTCP”).
In the hard disk conforming to the DTCP system, for example, the unlawful copy is prevented by the method by which encrypted data over a disk are copied in response to a demand from an external device and by which the information on the decoding key is given only to the external device recognized to be correct through an authentication. The copy protection information such as an authentication, key or cipher system is recorded in advance in the memory in the hard disk.
Here in the Unexamined Japanese Patent Application Publication No. Hei10-143443, there is disclosed the construction of a hard disk, the security of which is enhanced by using the data of a prepared password.
[Problems to be Solved]
In the case of the prior art, however, the memory having the copy protection information recorded in advance is directly connected with the bus line or the like. If this bus line is externally controlled, the key information or the like may be unlawfully stolen. If this key information or the like is stolen, the encrypted data can be decoded to perform the unlawful copy. A similar problem is pointed out not only for the hard disk but also for a data reproducing device for reproducing a data storing disk such as the CD or DVD.
Where the data reproducing device for the DVD or the like is to be made user-friendly, it is ordinarily necessary to purchase and customize a matching application software. However, there has been pointed out a problem that not only the software but also an external memory is required to raise the cost. A similar problem also arises when a personal computer is to be made user-friendly.